1. Field of the Invention
The present invention relates to an improvement of an FM stereo receiver, and specifically to an FM stereo receiver which controls the output signal level of the stereo multiplex circuit to cause an apparent improvement in channel separation.
2. Description of the Prior Art
When an FM stereo signal is received, an FM detection circuit is used to detect the FM broadcast signal. Also, a stereo multiplex circuit is used to separate the output signal from the detection circuit into left (L) and right (R) stereo signals which are amplified by a low frequency amplifier and then applied to the left and right speakers. In addition, three channel and four channel systems have also been proposed. In the conventional three channel system, a stereo sum signal (L+R) either contained in the FM detected output signal or generated by adding the separated left and right stereo signals is applied to a center speaker. In the four channel system the center speaker is further complemented by a rear speaker to which is applied a stereo difference signal (L-R) either contained in the FM detected output signal or generated by subtracting the separated left and right stereo signals. By thus increasing the audio channels, sound source position and direction can be improved.
However, simply increasing the audio channels as thus described is not enough, and systems which further enhance the stereo effect have been desired.